This invention relates to a process for preparing a confidential postcard. More particularly, it relates to a process for preparing a confidential postcard, wherein the confidential postcard composed of a certain paper sheet is capable of provisionally adhering by heating and pressurizing the paper sheet and is capable of being subsequently peeled off.
Heretofore, as means for advertisement for marketing or as means for communication in monetary organizations, such as banks, sealed letters enclosed in envelopes are resorted to in order to keep the written contents of postal matters confidential until they reach their destinations. However, with increase in the volume of the postal matters adapted to keep the written contents thereof confidential, it has been tried to conceal the written contents by resorting to postcards that are less expensive than the sealed envelopes. For this reason, various proposals have been made to date.
However, in order that a paper sheet may be handled as a postcard, the writing or printing surfaces of the overall postcard need to adhere in some or other way so as to be peeled off later. Thus, for concealing the written contents on the postal card, it has been proposed that the card be formed in plural layers which are caused to adhere provisionally by an adhesive so as to be peeled off later. However, this known method is economically unmeritorious because it is necessary to carry out the steps of application of an adhesive and subsequent processing. It is also necessary to carry out printing before applying the adhesive, while the dust and dirt may be deposited on the surface of the card coated with the adhesive, thus raising difficulties in handling. On the other hand, a paper sheet which may adhere simply by heating and pressurizing the paper sheet itself without using an adhesive has been disclosed in, for example British Patent 572,962 or U.S. Pat. No. 4,162,180. However, there lacks a concept in these prior-art publications that the paper sheet be used as a postcard, or that paper sheet may be peeled off with the statement previously inscribed on the attached adherent surface is retained, that is, the paper sheet may be attached provisionally. Hence, there is a demand for a confidential postcard which is not in need of an adhesive and which is capable of being peeled off with the statement on the paper sheet being left intact.